Process for coloring metallic copper



Patented Sept. 5, 1922.

. FREDERICK LAIsT, FREDERICK r. relax, EnNas'r KLarE'rKaflANn LYNDALL r. DAVIDSON, or ANAooNnA, MONTANA, Assre oas 'ro ANAooNnA corrnn MINING coMrANY, or ANAooNnA, MONTANA, A CORPORATION or MO rnoonss roa COLORING METALLIC corrnn.

Itl'o Drawing.

To all whom it may concern Be it known that We, FREDERICK LArsT, FREDERICK F. FRIGK, ERNEST KLEPETKO, and LYNDALL P. DAVIDSON, citizens of the United States, residing at Anaconda, in the county of Deer Lodge and State of Montana, have invented certain newand useful Improvements in Processes for Coloring Metallic Copper, of which the following is a specification. 7

This invention relates to the coloring of metallic copper by wet chemical processes.

It is the object of this invention to provide a process by which metallic copper used for structural or decorative purposes may be quickly and economically given certain desirable hues or colors of the order obtainable-only after an exposure of many years to atmospheric conditions.

. It is another'object to provide a process .by which a rel atively Wide range and diversity of colors may be obtained.

The process maybe carried out as fol lows: I v I The object to'be treated, for instance copper sheets for roofing, arefirst carefully pickled in hot dilute sulphuric acid. After washing they are suspended in an aqueous preferably saturated solution of copper nitrate and copper chloride. The time of immersion depends on the temperature of the bath. Fifteen minutes at 90 to 100 Cfand twelve hours at room temperature give equally good results. nitrate and chloride must contain no free acid. It usually contains basic copper salts in suspension. i v

4 After immersion under conditions as above mentioned the sheets, on removal, are

' cess or loose coating is rubbed off.

After washing the sheets are immersed in 'adilute caustic soda solution for approximately' ten minutes, after which they are washed .with water. and densified by the caustic soda treatment. The color varies from blue to a greenish blue depending uponlthe proportions of copper nitrate and cop-per chloride in the bath. In general the greenish hue increases with an increased proportion of copper chloride.

The bath of copper- The color is deepened.

Application filed November 29, 1921. Serial No. 518,647.

In order to obtain a wider range of colors,

the sheets after the caustic soda treatment may be immersed in a dilute ferrous sulphate solution. Depending'upon the time of immersion, a range from malachite green through olive green to, reddish brown may be obtained.

After the ferrous sulphate treatment the sheets are again washed;

Whenthe desired hue has been obtained, the coatlng is made permanent by immersion ina dilute solution of sodium silicate, followed by washing.

The coloring bath may be kept in conditlon for carrying out the process by addition of copper nitrate, copper chloride and nitric acid. Excess basic salts are dissolved by the nitric acid.

In the foregoing we have described what we consider the best manner of carrying out the invention. It should be. understood, however, that the process may be modified in varlous respects within the scope of the mvention.

The first three steps described serve the purpose of producing colored deposit, while the last step has the object to render the deposit insoluble.

The treatment with a mixture of copper nitrate and copper chloride followed by treatment with caustic sodaproduces abrilliant bluish-green which for certain purposes may be the ultimate color efi'ect desired.

The action of a copper nitrate solution alone when followed by a caustic soda treatment produces a color of the order of azuriteblue.

For certain purposes also this color may'correspond to the final effect desired.

- However for most practical purposes these colors are too pronounced and conspicuous and must be more or less modified by the application of av ferrous sulphate solution. It should be noted that while we prefer ferrous sulphate, which acts as 'a reducing agent, other reducing agents may be used, as for instance sodium oxalate or sodium sulphite which convert the bluish-green color produced by the first two steps de-. scribed above in detail to a yellow-green.

While we'consider sodium hydroxide as the commercial advantage of being a very cheap reagent. So far as the desired physical result of it is concerned, other substances, for instance sodium sulphite, might be used instead.

The process described with the various modifications of which it is susceptible has been developed primarily for the purpose of producing an artificial copper rust on copper shingles so as to give a copper roof initially a more pleasing predetermined permanent color effect. As above suggested, however, the process is equally applicable to the COlOIiIlg of other copper or cupriferous objects, for instance brass or bronze candlesti'cks, ash trays, and objectsor art in general where it is desired to antique the object, as well as brass shingles for a cheaper metal roofing material.

We claim:

1. In ,a process of producing a colored coating on cupriferous bodies including copper, the step which consists in subjecting a body to the action of a substantially c'oncentrated aqueous solution of a copper salt.

2. In a process of producing a colored coating on cupriferous bodies including copper, the step which-consists in subjecting a body to the action of a substantially concentrated aqueous solution of copper nitrate.

3. In a process of producing a colored coating on cupriferous bodies including copper, the step which consists in subjecting a body to.the action of a substantially concentrated aqueous solution of copper nitrate and copper chloride.

4. In a process of producing a colored coating upon bodies of metallic copper, the

step which consists in subjecting a body to the action of a substantially concentrated aqueous solution ofcopper nitrate and cop- 'per chloride.

5. In a-process of producing a colored coating on ,cupri'ferous bodies including copper, the steps which consist in subject ing a body'to the action of a substantially concentrated aqueous solution of a copper salt reacting with the body to produce thereon a basic copper salt deposit and then subjecting the body to the action of an aqueous solutionof an alkaline reagent.

'6. In a process of producing a coloredcoating on cupriferous bodies including copper, the steps which consistin subjecting a body to the actionof a substantially concentrated aqueous solution of copper nitrate and thereafter subjecting the body to the action of an aqueous solution of an alkaline reagent.

. 7. In a process of producing a .colored coating on cupriferous bodies including copper, the steps which consists in subjectting a body to the action of a substantially concentrated aqueous solution of copper nitrate and copper chloride and thereafter coating on cupriferous bodies including copper, the steps which consist in subjecting a body to the action of a substantially concentrated aqueous solution of copper nitrate and thereafter subjecting the body to the action of an aqueous solution of sodium hydroxide.

10. In a process of producing a colored coating on cupriferous bodies includingcopper, the steps which consist in subjecting a body to the action of an aqueous solution of copper nitrate and copper chloride and thereafter subjecting the body to the action of an aqueous solution of sodium hydroxide.

11; In a process of producing a colored coating on bodies of metallic copper, the steps which consist in subjecting a body to the action of a substantially concentrated aqueoussolution of copper nitrate and copper chloride and thereafter subjecting the body to the action of an alkaline reagent.

12. In a process of producing a colored coating on cupriferous bodies including cop per, the steps which consist in subjecting a body to the action of an aqueous solution of a copper salt reacting with the body to produce thereon a basic copper salt deposit and thereafter subjecting the body to the action of an aqueous solution of a reducing agent.

13. In a process of producing a colored coating on cupriferous bodies including cop per, the steps which consist in subjecting a body to the action of an. aqueous solution of a cop er salt reacting with the body per, the steps which consist in subjecting a body to the action of an aqueous solution of a copper salt reacting with the body to produce thereon a basic copper salt deposit and thereafter subjecting the body to the action of an aqueous solution of ferrous sulphate. a

. 15. In a process of} producing a colored coating on cupriferous bodies including copper, the steps which consist in subjecting a body to the action of an aqueous solution of a copper salt reacting with the body to produce thereon a basic copper salt deposit, then subjecting the body to the action of an aqueous solution of an alkaline reagent and then subjecting the body to the action of an aqueous solution of a reducing agent. 16. Process according to claim 13 in which the copper salt solution contains copper nitrate.

17. Process according to claim 13 in which the copper salt'solution contains copper nitrate and copper chloride.

18. Process according to claim 13 in which.

the reducing agent is ferrous sulphate.

19. Ina process of producing a colored coating on cupriferous bodies including copper, the steps which consist in subjecting the body to the action of aqueous solution of a copper salt reacting with the body to produce thereon a basic copper salt deposit and thereafter subjecting the body to the action of an aqueous solution of a salt reacting with the deposit formed to make it insoluble in Water.

20. Process-according to claim 17 in which the last mentioned salt is sodium silicate.

21. In a process of producing a colored coating on cupriferous bodies including copper, the steps which consist in subjecting the body to the action of aqueous solution of a copper salt reacting with the body to produce thereon a basic copper salt deposit, then I subjecting the body to the action of an aqueous solution of an alkaline reagent and thereafter subjecting the body to the action of a salt reacting upon the salt deposit to make it insoluble in water.

22. In a process of producing a colored coating on cupriferous bodies including copper, the steps which consist in subjecting the body to the action of aqueous solution of a copper salt reacting with the body to produce thereon a basic copper salt deposit,

thereafter subjecting the body to the action coating on cupriferous bodies including copper, which consists in immersing a body in an aqueous solution containing copper nitrate and copper chloride, then in an aqueous solution of sodium hydroxide, then in an aqueous solution of ferrous sulphate and then in an aqueous solution of sodium silicate.

In testimony whereof, we afiix our signa:

tures.

FREDERICK LAIST. FREDERICK F. FRIGK. ERNEST KLEPETKO. LYNDALL P. DAVIDSON. 

